Laminated electric condenser



Nov. 7, 1950 A. LIECHTI 2,528,597

LAMINATED ELECTRIC CONDENSER Filed March 24, 194B 2 Sheets-Sheet 1 INVENTORl /fzr feas/w.

ATTORNEY NOV. 7, 1950 A LlECH-rl 2,528,597

LAMINATED ELECTRIC CONDENSER *I INVENTOR k ,4455/87 Z/sc//fn ATTORNEY Patented Nov. 7, 1 950 UNITED "STATES, PATENT OFFICE 2,528,597 LAMINATED ELECTRIC CNDENSER Albert Liechti, zurich, switzerland, assigner t Micail A. G., Zurich-Altstetten, Switzerland, a corporation of Switzerland y Application March 24, 1948,v Serial No. 16,823

In Switzerland February 19,Y 1947 electric condenser of the type described in whichv glow eiects at the edges f the. metal foils are avoided and the dielectric property of the insulation material between the foils is fully utilized at all regions of said 'materialin the condenser. The capacity of acondenser according to the invention is considerably greater than that of a condenser in which the dielectric Yresistance is utilized fully at its bordery regions only. In the condenser according to theinvention the thickness of the dielectric is 'greater' at the border regions than at the central'region and this increased thickness is obtained in such manner as to avoid any undesirablebending of the layers of 4insulating material between 'and of the metal foils themselves when v'the' layers "are pressed closely together for eliminating any clearances therebetween.

' Itis an object of the present invention to pro# vide a thickened border region construction in electric condensers which permits maximum ine@ crease of thickness at a minimum of disturbance of the inner region of the condenser and of the metal foils and insulating laminae of which the condenser is composed. For this purpose additional, narrow pieces of insulating material are inserted between the Ineta'l foils" andthe dielectric material adjacent thereto at one side only of the full width dielectric material. The additional insulating material may consist of a relatively thick strip of insulating material or of a plurality of thin strips whereby the Width o fthe individual strips is diierent' for obtaining a stepwise-transition from the `th in inner portions of the condenser to the thickened border regions. v-Qlurther and other objects of the present invern-fv tion will be hereinafter set-forthl in theY accompanying specication and claims and shown in the drawings which, by wayof illustration, VshowV what I now consider to bepreferred embodiments of my invention. 1 v

. invention.

In the drawings: Fig. l is a transverse sectional perspective view of a composite condenser unit according to thel invention. v Fig; 2 is a diagrammatic transverse sectional illustration of a modified condenser unit accord;Y ing to the invention. y

Fig.m3 is a diagrammatic transverse sectional illustration of another modification of a con-y denser unit according to the invention.

Fgig. 4 is a diagrammatic transverse sectional illustration of a further modiiication of la condenser unit according to the invention. Fig. 5 is adiagrammatic transverse sectional view of yet another modification of a condenser;r

according to the invention.

Fig. 6 is a perspective view of a condenserac' cording to the invention.

Fig. 7 is a diagrammatic transverse sectional view oi a modined condenser according to the" Fig. 8 is a diagrammatic transverse sectional view of a modification of the construction shown' in Fig. 7'. "i Like parts are designated by like numerals iii all figures of the drawings.

rReferring more particularly to Fig. l of the drawings this shows a section througn'a strip of condenser material suitable to be wound to a coil and pressed. The strip is composed of strips of metal I'oil 2 with ive full width strips i o1" sheetlike `dielectric material therebetween. At 'th'e lateral border regions ofthe metallic foils 2 ad-v ditional, smallwidth strips of dielectric material 3`an d u are provided between one side, the underf side of the foils, and the `adjacent full widthI layer of insulating material. A set of insulating layers is shown not only between the two foils v2 butalso below the lower foil which latter set is designated by numeral l'. The strip of con-` denser `material of which Fig. 1 is a transverse section is wound into a' coil and the additional dii' electric I isprovided for assuring that; after winding, both sides of the foils 2 are separated from theneighboring foils by dielectric material o'f same characteristic.

Fig. 2 isa diagrammatic transverse sectionalf view ofA a modified arrangement according 4to the invention. For simplicitys Vsake the sections oi the metalstrips are shown in full lines and those of the dielectricmaterial are shown in dash-doti lines. Additional, small Width insulating material 3', 4 is inserted adjacent the under side of one border region only of the foils 2 and 2", respectively; at the other border region additional, small width insulating material 3", 4 is inserted at the upper side of the metal laminae 2 and 2, respectively. The additional material consists ineach case of three superimposed strips of insulating material whereby the Width of the strips is diierent; the narrowest strip is placed directly adjacent a metal foil and the others are layed on one another in the order of increasing width. This produces gradual increase of thickness of the dielectric at the border regions. The full width dielectric l consists of four layers of insulating material I In the embodiment of the invention according to Fig. 3 the intermediary, small width insulating strips 5 to 8v are each composed of three layers of different width wherebynthe narrowest is placed adjacent the full width dielectric I which is composed of three layers of insulating material, and the widest is placed adjacent the foils 2 or 2". Also in this modification there is supplemental insulating material for thickening the border regions inserted at one side only of a border portion of the full width dielectric. The difference between the arrangement according to Figs. Zand 3 is inthe fact that in the former the additional insulating material is placed alternatively at one end and then atthe other border reg-ion, not only with respect to the two sides of each dielectric package I, I but also with respect to the sides of the foils 2', 2", whereas in the latter the alternate feature applies only with respect to the dielectrics I, I. The right edge of foil 2 is between two narrow supplemental strips of dielectric 5, 'I and the left edge of foil 2 is, after coiling, between they supplemental layers 6 and B.

Packages of small width stripsv as illustrated in Fig. 2 may be used in the arrangmentv according to Fig. 3 and vice versa; Likewise, the number Vof narrow layers composing an intermediary insulating package and the number of full width dielectricY layers between two foils may be changed without departing from the scope of the present invention.

' It is' known that the' voltage at which acondenser can be operated-is proportional to the square root of' the' thickness of the dielectric; that the power that the condenser can accumulate is the product 'of tension 'and currentv and is'proportional to the square of the ionization tension. y

Tests have shown that thickening of the border regions relatively to the inner region of a condenser by the factor n'permits an increase of the operating voltage by the factor \/1L, provided that the insulating resistance of the dielectric in the central region withstands this increased voltage. The power of the'conde'nser according to the invention is increased by the factor n.

Ifthe thickened portions of the dielectric are subdivided into halves betweentwo metallic layers 9 by narrow intermediary strips of foil I0 as shownin Fig. 4, asis done in conventional condensers, the permissible operating voltage is increased by the factor Vin-,andthe permissible operating power by the factor 2n. An increase of thickness of the border regions by, for eX- ample, 40% whereby Vn amounts to 1.4, and injsertion oi narrow additional metallic linings results in a possible increase of the operating volt- 4 age by the factor \/2 1.4 and an increase of power by the factor 2.8.

The narrow additional metallic linings need not consist of independent foils, the metal may be preferably steamed, pressed or sprayed to the respective insulating layers whereby the metal forming a narrow additional coating at both borders of the same dielectric layer may be conductively connected as shown in Fig. 4 whereby homogeneous distribution of electric tension is obtained over the whole massof the Ythickened di electric; In the modication shown in Fig. 4 the metallic laminae 9 project alternately from one side of the dielectric which produces better cooling than the modifications according to Figs. 1 to 3 where the foils are fully embedded in the dielectric.

The arrangement of layers diagrammatically illustrated in' Fig. 3 may be modied according to Fig. 5 by ymaking the small width layers 5, 1 and 6, 8 in one piece and wrapping them around the lateral edges of the metallic laminae 2', 2 as' indicated by numerals II and l2 in Fig. 5. This figure illustrates diagrammatically a composite condenserstrip vaccording to the Ainvention after it has been folded' over once.- The trans`A verse'section of astrip` before-fitis rolled and pressed looks, for example, like 'the section with-v in the dotted-line rectangle Fig. 5.

The condenser coils woundA of 'composite' strips madel according to `one of the 'Figures l toj5 are preferably flattened by compression whereby all layers are firmly pressed together without clearances in the inner portion as Well .as-in the border portions: The` resulting'flattened coil or roll has substantially a configuration as per Fig. 6 lof the drawings. Even With'niaximum increase of the 'thickness' of' thev border regions I3;l I4 'the' roll takes hardly mo'respace than a nat/roll hav'-J ing no thickened border; however, the capacity of a condenser having the dielectric enlarged 'at its border regions is four times vas great than that of a conventional condenser;

Fig.. illust'raltes'A all' embodiment 'of the in:- venti'on which makesjconipre'ssing of the' con'- denser unnecessary. 'In this'case at least some of the metallic layersV are composed'of two foils having theirborde'r regions parallel and closely adjacent one another and having insulating in aterial between their parallel center portions. vInthe embodiment 'of' the" invention illustrated in' Fig. '7, the metallic laminae are alternately split, laminae I6, and unsplit, laminae I5'. Thespa'ce produced by `splitting 'the center portion 'of laminae I6 is lled W'ithan' insulating ledrr'' IT. The transition from the splitV center portionla to the linsplit-bordr portions is gradual and conforms with the inner portion'gof 'the small Width packagesA` of insulating layers I9. The fll width dilectri'clamina'e 2'0 are' closely adjacent the center portion I8' of the metallic laminael and the spaces between the border regions of the y rrl'etallo laminae I6 and of 'the full. width insulatig`."l'sl'` s diagrammatically a transvrsesection of tw' adjacent composite condenser units' according. to the invention such `as 'may be obtained by folding kstriplike unit once. -"I he matter shown within the dotted linev rectangle indicates a transverse section through a composite condenser strip according to the invention suitable to be coiledto-form a condenser roll. -In the diagrammatic showing of Fig. -7 thespace.

in the interior of the split laminae I6 is much exaggerated.

The capacity of a condenser as illustrated, diagrammatically, in Fig. 7 corresponds about to that of a condenser of same dimensions :but having no additional dielectric at its border regions and having a distance a between the metal laminae. The increase of thickness of the dielectric at the border regions of the condenser according to the invention amounts to whereby A is the distance between two'foils.

Many modifications of the relative layer arrangements are possible within the scope of the .present invention. For example, in the modification shown in Fig. 7 the central portion of all metallic layers may be split and layers l be omitted.

Fig. 8 diagrammatically shows an arrangement whereby the metallic laminae consist of a plane portion 2l and a portion 22 having curved lateral borders 23 united with the edges of sheet member 2l. The space 24 between parts 2| and 22 is lled with insulating material.

Manufacture of condensers according to Figs. 7 and 8 is somewhat more diflicult than that of pressed rolls, but they have the advantage of a denitely Xed configuration of the metallic laminae at the region of transition from the central to the border portions.

While I believe the above described embodiments of my invention to :be preferred embodiments, I wish it to be understood that I do not desire to be limited to the exact details of design and construction shown and described, for obvious modifications will occur to a person skilled in the art. Y

I claim:

1. An electric roll condenser comprising dielectric masses having each a relatively thin central portion and relatively thick lateral border portions, longitudinal metallic layers composed of two laminae joined :it their lateral border por tions and spaced from one another at their central portions and individually interposed between always two of said masses, said masses comprising each a full width insulating layer abutting at its central portion a side of said metallic layers, and

an additional small width package of insulating material disposed between a side of a border portion of said full width insulating layer and a border portion of one of said metallic layers.

2. An electric roll condenser as dened in claim 1, the space between the two laminae forming one metallic layer being lled with insulating matter.

3. An electric roll condenser comprising dielectric masses having each a relatively thin central portion and relatively thick lateral border portions, longitudinal metallic layers composed of two laminae joined at their lateral border portions and spaced from one another at theirv central portions, individual metallic laminae, said metallic layers and said metallic laminae being alternately individually dispersed between always two of said masses, said masses comprising each a full width insulating layer abutting at its central portion the sides of one of said metallic layers and one of said individual laminae facing one another, and an additional small width package of insulating material disposed between a side of a border portion of said full width insulating layer and a border portion of one of said metallic layers.

4. An electric roll condenser as defined in claim 1, one of said laminae of said metallic layers being straight in its transverse direction.

5. An electric roll condenser comprising, in combination, metallic laminae, a dielectric mass interposed between each two metallic laminae and comprising a full width portion composed of a plurality of full width insulating layers and having two lateral marginal portions and comprising at least one small width insulating layer disposed at one side of said full width portion at a lateral marginal portion thereof and between said side and a metallic lamina and comprising at least one other small width insulating layer disposed at the other side of said full width portion and at the other lateral marginal portion thereof.

6. An electric roll condenser comprising, in combination, metallic laminae having two lateral marginal portions, a plurality of full width oil impregnated insulating sheets interposed between each two metallic laminae, at least one narrow strip of oil impregnated insulating sheet material interposed between one side at one lateral portion of said metallic laminae and an adjacent full width insulating sheet, and at least one narrow strip of oil impregnated insulating sheet material interposed between the other side at the other lateral portion of said metallic laminae and an adjacent full width insulating sheet.

ALBERT LIECHTI.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS 

